“Do I really look like a guy with a plan? You know what I am? I’m a dog chasing cars. I wouldn’t know what to do with one if I caught it. You know, I just… do things. The mob has plans, the cops have plans, Gordon’s got plans. You know, they’re schemers. Schemers trying to control their little worlds. I’m not a schemer. I try to show the schemers how pathetic their attempts to control things really are.”
Harvey Dent is an interesting character, because as the D.A., he values and fights for this same order as Batman. However, as symbolized by the two-sided coin, there was a there romanticized view of chaos, and its complementary role in a truly fair order. So Harvey Dent/Two-Face was the living embodiment of the struggle between the light and the darkness, the order and the chaos. Later in their discussion, The Joker expands on his role:
“Introduce a little anarchy. Upset the established order, and everything becomes chaos. I’m an agent of chaos. Oh, and you know the thing about chaos? It’s fair.”
So we see this battle between the Apollonian/Batman force and the Dionysian/Joker force for the heart and soul of Harvey Dent. Everything Dent has fought for came crashing down, and The Joker strikes a chord with him — paving the way for the transition into Two-Face.
What is probably the strongest symbolic imagery the film offers is the scene wherein Batman finally captures The Joker:
Batman and The Joker are facing (The Joker upside down), which makes for a very yin-yang imagery: as above, so below. The Joker reveals that he doesn’t want to destroy Batman. He needs Batman. And they are destined to partake in this Apollonian/Dionysian duality duel for eternity. Their Nietzschean relationship has come full circle.
The Joker: Oh, you. You just couldn’t let me go, could you? This is what happens when an unstoppable force meets an immovable object. You are truly incorruptible, aren’t you? Huh? You won’t kill me out of some misplaced sense of self-righteousness. And I won’t kill you because you’re just too much fun. I think you and I are destined to do this forever.
Batman: You’ll be in a padded cell forever.
The Joker: Maybe we can share one. You know, they’ll be doubling up, the rate this city’s inhabitants are losing their minds.
Batman: This city just showed you that it’s full of people ready to believe in good.
The Joker: Until their spirit breaks completely. Until they get a good look at the real Harvey Dent and all the heroic things he’s done. You didn’t think I’d risk losing the battle for Gotham’s soul in a fist fight with you? No. You need an ace in the hole. Mine’s Harvey.
Batman: What did you do?
The Joker: I took Gotham’s white knight and I brought him down to our level. It wasn’t hard. You see, madness, as you know, is like gravity. All it takes is a little push!
The film ends with Batman, who himself has disrupted the order of Gotham City, despite being the Apollonian figure, realizing that he must operate outside of the order, in order to enforce order. This makes him an even greater supernatural figure, rather than simply a crime-fighter. He is a deified force of Gotham and is the Order. He will constantly battle the agents of chaos in an eternal battle for Gotham’s soul. Apollo is thus the Dark Knight.